1. Field of the Invention
This invention relates to a rolling wheel support structure for a crawler traveling apparatus used as traveling apparatus for an agricultural machine, a construction machine or the like.
2. Description of the Prior Art
This kind of crawler traveling apparatus is formed by providing a driving wheel and a driven wheel at front and rear sides of a track frame, a plurality of rolling wheels on a lower portion of the track frame, and wrapping around these wheels a metal crawler provided with a multiplicity of iron shoes on the outer circumferential portions of chain links or an elastic crawler made of an elastic material, such as rubber. This kind of crawler traveling apparatus is designed so as to improve the traveling characteristics thereof with respect to a soft land and a desolate land by increasing an area of the crawler contacting a ground surface to reduce a ground pressure.
Since the crawler traveling apparatus has a high probability of traveling on soft land and desolate land, large vibrations of the traveling apparatus occur due to the irregularity of the ground surface resulting in the problem of the deterioration of riding comfort, Therefore, it is an important problem in the development of crawler traveling apparatus to improve the riding comfort by eliminating the causes of such vibration.
The measures which have heretofore been taken to eliminate the causes of such a vibration include the measures disclosed in, for example, Japanese Unexamined Utility Model Publication No. 42503/1976. These measures use a structure formed by fixing an elastic material, such as rubber, on outer circumferential surfaces of rolling wheels by burning; and then providing protective covers on outer circumferential portions of this elastic material. Owing to this structure, the elastic material provided between an inner circumferential surface of a crawler and the rolling wheels absorbs the vibrations, and the riding comfort can be improved to some extent.
However, in this structure, since the elastic material is provided on the outer circumferential surfaces of the rolling wheels, the protective covers are needed. Even when the protective covers are provided in practice, the occurrence of abrasion and defects of the rolling wheels cannot be avoided since the rolling wheels always roll on the crawler. Moreover, burning of the elastic material on the rolling wheels causes an increase in the manufacturing cost which is a drawback for these techniques.
In view of these problems, it is an object of the present invention to provide a rolling wheel support structure for a crawler traveling apparatus capable of effectively improving the riding comfort of a crawler by properly absorbing the vibration thereof due to the irregularity of a ground surface.
According to one aspect of the present invention, there is provided a rolling wheel support structure for a crawler traveling apparatus, which includes rotary shafts rotatably supporting rolling wheels that roll on a ground contacting side of an inner circumferential surface of an endless crawler, a track frame supporting the rotary shafts, and a buffer member made of an elastic material and provided between the track frame and a rotary shaft.
According to the above structure, the vibration of the crawler due to the irregularity of the ground surface is properly absorbed in the buffer member provided between the track frame and the rotary shaft, and the riding comfort is improve. Since the buffer members do not directly contact the inner circumferential surface of the endless crawler, deterioration of the buffer member caused by abrasion or the like decreases.
In this structure, it is preferred that the rotary shaft be provided on the track frame so that the rotary shaft can be vertically moved, that a receiving member be provided on the rotary shaft; and that a buffer member be provided between an upper portion of the receiving member and a lower portion of the track frame. This construction provides for a vibration-proof structure for the crawler traveling apparatus that is simple and inexpensive to build.
According to another aspect of the present invention, there is provided a rolling wheel support structure for crawler traveling apparatus which includes a swinging member rotatably supporting a rolling wheel that rolls on an inner circumferential surface of a lower ground contacting side of an endless crawler, a pivot pivotably supporting the swinging member, a track frame supporting the pivot, and a buffer member provided between the track frame and the pivot.
According to the above structure, the vibration of the crawler traveling apparatus due to the irregularity of a ground surface is properly absorbed in the buffer member between the track frame and the pivot such that the riding comfort is improved.
With this structure, it is recommended that the track frame be provided with a cylindrical support member capable of being fitted around the buffer member, and that the buffer member has a cylindrical shape such that the pivot can be fixed into the buffer member such that it is impossible to turn the pivot relative to the buffer member around the axis thereof.
With this structure, the vibration of the crawler can be absorbed in the buffer member while the swinging member is maintained in a pivotable condition.
In this later embodiment, it is preferable that a swinging member fixing shaft is formed to a shape of a square shaft and an inner surface of the buffer member is formed to a shape in conformity with the shaft in cross-section.
Moreover, the buffer member preferably includes larger-diameter portions and smaller-diameter portions which alternate in the axial direction
Although the buffer member can be provided for all the rolling wheels, the buffer member may also be provided for only a rolling wheel provided at a front or rear portion of the crawler traveling apparatus, or, correspondingly, be provided to only a rolling wheel located at a longitudinally intermediate position of the crawler traveling apparatus.
When a working machine, such as a combine, is swung, a front or rear portion of a crawler traveling apparatus stands firm, and the machine as a whole swings longitudinally in some cases. However, when the buffer member of the invention is provided in a rolling wheel positioned at the first portion or rear portion of the crawler traveling apparatus, the swinging phenomenon can be avoided by use of the buffer member. When the buffer member is provided on a rolling wheel at a longitudinally: intermediate position of the crawler traveling apparatus, the rolling wheel can be pressed against the inner circumferential surface of the lower portion of the endless crawler by the buffer member, when by a ground pressure of the longitudinally intermediate portion of the crawler partly increases, and a pivotal or swinging movement of the working machine around the crawler can be carried out smoothly.